Year 12 Bio - Periods 46-47

The text describes an investigation using the enzyme catalase. What reaction does catalase speed up?

• The breakdown of starch into maltose.

• The breakdown of hydrogen peroxide into water and oxygen.

• The joining of amino acids to form a protein.

• The synthesis of glucose.

In the catalase experiment, how is the rate of reaction measured?

• By measuring the change in colour of the solution.

• By measuring the volume of oxygen collected over time.

• By measuring how quickly the substrate disappears.

• By measuring the change in temperature.

According to the graph for the catalase reaction, when is the reaction rate the fastest?

• At the very beginning of the reaction.

• After about 180 seconds.

• At the end of the reaction.

• The rate is constant throughout.

Why does the rate of an enzyme-catalysed reaction slow down over time?

• The enzyme gets used up.

• The temperature decreases.

• The concentration of the substrate decreases.

• The product inhibits the enzyme.

How can the 'initial rate of reaction' be calculated from a graph of product formed against time?

• By finding the highest point on the curve.

• By calculating the slope (gradient) of the curve at the beginning (close to time 0).

• By dividing the total product formed by the total time.

• By finding the time it takes for the reaction to stop.

The text describes a second experiment using the enzyme amylase. What is the substrate for amylase?

• Oxygen

• Hydrogen peroxide

• Protein

• Starch

In the amylase experiment, how can the progress of the reaction be monitored?

• By collecting the gas produced.

• By measuring the disappearance of the starch using iodine solution.

• By measuring the change in pH.

• By weighing the amount of enzyme remaining.

What instrument is used to get quantitative measurements of the colour change in the amylase experiment?

• A microscope

• A gas syringe

• A colorimeter

• A thermometer

What does a colorimeter directly measure?

• The concentration of a solution.

• The temperature of a solution.

• The absorption of light by a solution.

• The pH of a solution.

In the amylase experiment, as the starch is broken down, what happens to the intensity of the blue-black colour?

• It increases.

• It stays the same.

• It decreases.

• It turns red.